Bump minrelaytxfee default

To bridge the time until a dynamic method for determining this fee is
merged.

This is especially aimed at the stable releases (0.10, 0.11) because
full mempool limiting, as will be in 0.12, is too invasive and risky to
backport.

Github-Pull: #6793
Rebased-From: 28e3249e53 4e2efb3c5f

src/main.cpp

@@ -56,7 +56,7 @@ unsigned int nCoinCacheSize = 5000;
 bool fAlerts = DEFAULT_ALERTS;
 
 /** Fees smaller than this (in satoshi) are considered zero fee (for relaying and mining) */
-CFeeRate minRelayTxFee = CFeeRate(1000);
+CFeeRate minRelayTxFee = CFeeRate(5000);
 
 CTxMemPool mempool(::minRelayTxFee);
 

src/test/transaction_tests.cpp

@@ -341,7 +341,7 @@ BOOST_AUTO_TEST_CASE(test_IsStandard)
     t.vout[0].nValue = 501; // dust
     BOOST_CHECK(!IsStandardTx(t, reason));
 
-    t.vout[0].nValue = 601; // not dust
+    t.vout[0].nValue = 2730; // not dust
     BOOST_CHECK(IsStandardTx(t, reason));
 
     t.vout[0].scriptPubKey = CScript() << OP_1;